Expandable piston for internal combustion engines



April 28, 1959' J. H. MORROW\ 7 2,884,290

- EXPANDABLE PISTON FOR INTERNAL COMBUSTION ENGINES Filed July 12, 195'? Joseph Homer Morrow INVENTOR.

United States Patent EXPANDABLE PISTON FOR INTERNAL COMBUSTION ENGINES Joseph Homer Morrow, Woodlawn, Tenn. Application July 12, 1957, Serial No. 671,437 6 Claims. (Cl. 309-10) The present invention generally relates to a novel piston construction specifically adapted for internal combustion engines but may be employed with any type of reciprocating power device and incorporates a feature which provides for the expansion of the piston into engagement with a cylinder for taking up any wear of the cylinder or piston and providing a more effective seal therebetween.

In the conventional internal combustion engine, cylindrical pistons are employed in a cylinder with rings bridging the gap between the piston and cylinder for sealing the piston to the cylinder whereby the combustion on top of the piston will effectively force the piston in a direction of movement rather than blowing by the piston. The cylindrical pistons and cylinders have been subject to considerable wear and consequent repair cost and inefficient operation. Accordingly, it is the primary object of the present invention to provide a substantially square piston for use in a similar shape cylinder and incorporates in its construction, four substantially identical wall members having edges telescopically engaged and having the top edges engaged with a piston head whereby spring means is provided for urging the walls outwardly so that the rings on the walls will be in intimate contact with the cylinder at all times.

Another object of the present invention is to provide a piston construction in accordance with the preceding object in which guide means is provided for guiding the relative sliding movement of the members forming the piston with the head of the piston being sealed to the top edges thereof.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is a perspective view of the piston construction of the present invention;

Figure 2 is a transverse sectional view taken substantially upon a plane passing along the center line of the piston bosses;

Figure 3 is a plan view of the top of the piston with portions thereof broken away showing the details of construction thereof;

Figure 4 is a sectional view taken substantially upon a plane passing along section line 4-4 of Figure 5 illustrating the details of the interlapping joints;

Figure 5 is a transverse plan sectional view taken substantially upon a plane passing along section line 55 of Figure 2; and

Figure 6 is a perspective view of one of the wall members.

Referring now specifically to the drawings, the square piston of the present invention is generally designated by the numeral 10 with the peripheral wall generally designated by the numeral 12 being made up of four "ice L-shaped sections or elements generally designated by the numeral 14 and specifically shown in Figure 6. Each of the sections 14 is provided with a vertically elongated and transversely elongated portion 18 and a relatively transverse short portion 16 extending perpendicular thereto. Adjacent the juncture between the portions 16 and 18, a pair of projecting guide pins 20 is provided on the portion 16 and a pair of projecting guide pins 22 is provided on the portion 18.

The top edge of the section 14 extends inwardly as designated by the numeral 24 and is provided with a groove 28 in the inner edge thereof and also a groove 30 in the top surface thereof adjacent the outer edge.

The edge of the transversely elongated portion 16 is provided with a pair of projections 32 at the top and bottom edge thereof respectively with a recess 34 being disposed in the center thereof with the recess 34 and projections being centralized on the edge. The free edge of the portion 18 is provided with a centrally disposed projection 36 and a pair of recesses 38 at the top and bottom thereof for telescopic engagement with the projections 32 and recess 34 respectively whereby a sliding joint is provided with the joint formed by the projections and recesses being continuous and sealed and enabling the lengthening of the side walls of the piston 10 when wear occurs.

Extending between and encircling opposed pairs of pins 20 and 22 is a series of compression coil springs 40 urging the wall sections 14 outwardly into engagement with the wall of a cylinder. The pins terminate in adjacent relation for preventing buckling of the springs. All of the wall sections 14 are provided with peripheral oil control grooves 42 which extend about the periphery of the piston 10 for preventing oil passage between the piston and cylinder but providing sufficient lubrication for the piston.

Each of the sections 14 are identical in construction except that one pair of opposed sections 14 is provided with inwardly extending cylindrical bosses 44 having piston pin receiving bores 46 extending therethrough for receiving a piston pin 48 having a connecting rod 50 connected thereto as shown in phantom in Figure 2.

The bearing area provided by the bearing wall surfaces of the telescoped projections prevent inward or outward bowing of the piston walls thereby maintaining a flat outer surface for each piston wall.

A piston head or top member is provided and designated by numeral 60, with the periphery of the top 60 extending flush with the walls of the piston when the piston is completely collapsed. The top or piston head 60 is provided with an annular inwardly extending groove 62 having a shorter lower edge than upper edge as clearly shown in Figure 2 for telescopically and slidably receiving the inwardly extending edge 24 on the upper end of the sections 14. The upper wall of the groove 62 is provided with a groove 64 for matching engagement with the groove 30 for receiving an O-ring seal 60 therein for sealing the top 60 to the sections 14. Also, a similar O-ring seal 68 is disposed in the groove 28 and a similar groove in the bottom of the annular groove 62 thus forming a double seal for the piston.

The piston of the present invention operates in substantially the same manner as the conventional piston except that the sections are expandable into constant engagement with the matching surfaces of a cylinder of the same shape whereby any wear occurring in either the piston or cylinder will be taken up by the springs urging the sections of the piston outwardly. Also, the increased lubrication qualities and the long lasting qualities will substantially reduce the maintenance cost of internal combustion engines and eliminate the loss of power by blow by and also substantially eliminate the burning of oil which occurs when the pistonsand cylinder .donot properly seal the lubricating oil from the combustion products. The piston may be constructedof any suitable material but is preferably constructed of materials similar to that employed in pistons for internal combustion engines, compressors, pumps or anyother use forwhich pistons are employed.

The piston 60 may be split into upper and lower sections by a plane of division incommunication with the groove 62. The upper and lower sections may be secured together by employing bolts or other suitable accessible fastening means for permitting assembly of the sections on the side walls after the sections 14 .have been assembled.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as: follows:

1. A piston construction,for-reciprocating movement in a cylinder comprising four L-shaped vertically elongated members, means slidably interconnecting the edges of said membersto permit expansion and contraction thereof, spring means extending between opposed members for urging the same outwardly, one pair of opposed members having piston pin receiving bores, and a piston head slidably connected with the top edgeof each L- shaped member, said'slidableeonnection between the L- shaped members and said 'piston head including seal means.

2. The combination gofgclaim .1 whereinsaid .slidable connection between the edges of the L-shaped members includes a plurality of telescopic interdigitated and projections and recesses disposed centrally onthe edges of the members for providing lateral stability to the sections.

3. The combination of claim 1 wherein said piston head is provided with an annular groove having the lower edge thereof disposed inwardly of the top edge, each of said L-shaped members having an inwardly extending upper edge slidably received in said groove.

4. The combination of claim 3 wherein the top wall of said groove is provided with an O-ring seal in engage ment with the top surface of the inwardly extending upper edges of the L-shaped members.

5. A piston for an internal combustion engine for reciprocation in a cylinder comprising four identical angulated sections having relatively slidable telescopic edges to permit expansion and contraction thereof and coacting to form a square piston, opposite of said sections having piston pin bosses therein, spring means urging said sections outwardly forintimatecontact with a cylinder wall, and a piston head slidably, sealingly engaged with the upper edges of said outwardly movable sections.

6. A piston construction for reciprocating movement in a cylinder comprising four verticallyelongate members, means slidably interconnecting the edges of said members to permit expansion and contraction thereof, spring means extending between opposed members for urging the same outwardly, one pair of opposed'members having piston pin receiving bores, and a piston head slidably connected with the top edge of each member, said slidable connection between the members and said piston head including seal means.

References Cited in thefile of this patent UNITED STATES PATENTS 386,011 Holmgren July 10, 1888 1,728,514 Snyder Sept.'17, 1929 2,064,756 Janeko Dec. 15, 1936 

